proxy.ts

import { NextResponse, type NextRequest } from 'next/server';
import { isProduction } from '@/lib/seo/env';

/**
 * Environment isolation at the edge of the app.
 *
 * In Next.js 16 "middleware" was renamed to "proxy" (it runs in the Node.js
 * runtime, ahead of your app). This file is the Next.js 16 equivalent of the
 * `middleware.ts` the spec describes.
 *
 * Responsibility: any NON-production deployment (preview/staging) gets
 * `X-Robots-Tag: noindex, nofollow` on every response, so a preview URL can
 * never be indexed even if it is publicly reachable. The check reads the live
 * environment at request time, so the same build behaves correctly whether it
 * is started as production or preview.
 */
export function proxy(_request: NextRequest): NextResponse {
  const response = NextResponse.next();

  if (!isProduction()) {
    response.headers.set('X-Robots-Tag', 'noindex, nofollow');
  }

  return response;
}

export const config = {
  // Run on everything except Next internals and static assets.
  matcher: ['/((?!_next/static|_next/image|favicon.ico).*)'],
};